Generally, in order to fabricate a desired semiconductor device, various heat treatment processes such as a film forming process, a pattern etching process, an oxidation/diffusion process, a quality modification process, an annealing process and the like are repeatedly performed on a semiconductor device. With a recent trend towards a high-density, a multilayered structure and high-integration of the semiconductor device, means employed therefor has been getting more tightly restricted, and especially, an improvement of in-surface uniformity and film quality of the wafer has been demanded in such various heat treatment processes. For example, in case of processing a channel of a semiconductor device, e.g., a transistor, after ion-implantation of impurity atoms into the channel, an annealing process is generally carried out to stabilize the atomic structure.
In this case, if the annealing process is performed for a long period of time, the atomic structure can be stabilized, but at the same time, this allows for the impurity atoms to diffuse deeply in a film thickness direction to penetrate throughout the channel. Thus, to suppress the diffusion of the impurities, it needs to be performed in the shortest possible time. That is, in order to stabilize the atomic structure with the channel having a thin thickness without having the impurity atoms to penetrate throughout, it is necessary to rapidly raise the temperature of the semiconductor wafer to a high temperature, and further, after completing the annealing process, to rapidly lower it to a low temperature where diffusion does not occur.
For this annealing process, lamp annealing using a heating lamp is generally carried out in the conventional processing apparatus (see, U.S. Pat. No. 5,689,614).
Further, another conventional processing apparatus wherein a wafer stage is provided with a peltier element used to raise or lower a temperature of a wafer in the etching process performed in the range between 100° C. and 250° C. is disclosed, for example, in Japanese Patent Laid-open Application No. 2001-85408.
Recently, a semiconductor light emitting element such as an LED device, a laser device or the like with a relatively large output tends to be popularly used as a heating source or a light source (see, Japanese Patent Laid-open Application No. 2004-296245, Japanese Patent Laid-open Application No. 2004-134674, and U.S. Pat. No. 6,818,864). The LED or laser device is widely used because loss due to heat generation of the device itself is much smaller than that of the heating lamp, and the lifetime thereof is considerably longer than that of the heating lamp.
For example, Japanese Patent Laid-open Application No. 2004-296245 discloses a lamp formed by combining a heat pipe with an LED device, and Japanese Patent Laid-open Application No. 2004-134674 discloses that a resist is heated by using an LED or laser device, while U.S. Pat. No. 6,818,864 discloses an LED array used to perform a CVD process.
However, in case of performing a heat treatment as described above, in-surface temperature uniformity of the wafer has to be maintained. Particularly, in case of the oxidation/diffusion process, a temperature of the wafer needs to be rapidly raised or lowered in a short time to prevent excessive diffusion of the implanted impurities.
Further, in the conventional apparatus described above, for example, in the case of using the LED device, it is possible to rapidly raise the temperature of the wafer in the same manner as in the lamp heating. Further, since the device itself is not so heated, contrary to the lamp heating, the temperature of the wafer can be lowered at a relatively high speed.
However, as a design rule of a line width, a film thickness or the like becomes strict, the temperature of the wafer is required to be controlled at a high speed, but it is not possible to rapidly lower the temperature by using the above-mentioned conventional apparatus, which cannot cope with the new design rule.